1. Field of the Invention
This invention relates to attrition resistant metal/oxygen compositions and a process for preparing such compositions. More particularly, this invention relates to metal/oxygen compositions comprising the infusion and reaction product of:
(a) an alumina existing in a crystal form selected from the group consisting of .gamma., .delta., .eta., and .chi. crystal forms, and mixtures thereof, or that can be transformed by heat to such crystal forms, and characterized by PA1 (b) at least one metal oxide, or compound convertible by heat to such metal oxide, having a maximum mean particle size of about 100 .mu.m, with the proviso that the alumina/metal oxide mean particle size ratio is at least 2, which metal oxide is susceptible of undergoing infusion and reaction with the alumina upon being subjected to temperatures of at least 0.4 T.sub.m for a time sufficient to cause infusion and reaction between the metal oxide and the alumina, wherein T.sub.m is the melting point in .degree.K. of the alumina. PA1 (a) an alumina existing in a crystal form selected from the group consisting of .gamma., .delta., .eta., and .chi. crystal forms, and mixtures thereof, or that can be transformed by heat to such crystal forms, and characterized by PA1 (b) at least one metal oxide, or compound convertible by heat to such metal oxide, having a maximum mean particle size of about 100 .mu.m, with the proviso that the alumina/metal oxide mean particle size ratio is at least 2, which metal oxide is susceptible of undergoing infusion and reaction with the alumina upon being subjected to temperatures of at least 0.4 T.sub.m for a time sufficient to cause infusion and reaction between the metal oxide and the alumina, wherein T.sub.m is the melting point in .degree.K. of the alumina. The provision of the process for the preparation of such compositions objects is achieved by a process which comprises: PA1 (a) forming a mixture of an alumina existing in a crystal form selected from the group consisting of .gamma., .delta., .eta., and .chi. crystal forms, and mixtures thereof, or that can be transformed by heat to such crystal forms, and characterized by PA1 and at least one metal oxide, or compound convertible by heat to such metal oxide, having a maximum mean particle size of about 100 .mu.m, with the proviso that the alumina/metal oxide mean particle size ratio is at least 2, which metal oxide is susceptible of undergoing infusion and reaction with the alumina, and PA1 (b) heating the mixture to a temperature of at least 0.4 T.sub.m for a time sufficient to cause infusion and reaction between the metal oxide and the alumina, wherein T.sub.m is the melting point in .degree.K. of the alumina. The provision of the toluene dehydrocoupling process object is achieved by a process which comprises: PA1 (a) contacting the toluene in the vapor phase at a temperature from about 450.degree. C. to about 650.degree. C. with an attrition resistant metal/oxygen composition comprising the infusion and reaction product of PA1 (b) recovering the toluene dehydrocoupled product. PA1 (a) an alumina existing in a crystal form selected from the group consisting of .gamma., .delta., .eta., and .chi. crystal forms, and mixtures thereof, or that can be transformed by heat to such crystal forms, and characterized by PA1 a maximum mean particle size of about 100 .mu.m, with the proviso that the alumina/metal oxide mean particle size ratio is at least 2, which metal oxide is susceptible of undergoing infusion and reaction with the alumina upon being subjected to temperatures of at least 0.4 T.sub.m for a time sufficient to cause infusion and reaction between the metal oxide and the alumina, wherein T.sub.m is the melting point in .degree.K. of the alumina.
(i) a mean particle size from about 10 .mu.m to about 200 .mu.m, PA2 (ii) a fractional porosity of at least 0.2, PA2 (iii) a surface area of at least 150 m.sup.2 /g, and PA2 (iv) a pore diameter such that at least 10 percent of the pores are less than 55 .ANG., and PA2 (i) a mean particle size from about 10 .mu.m to about 200 .mu.m, PA2 (ii) a fractional porosity of at least 0.2, PA2 (iii) a surface area of at least 150 m.sup.2 /g, and PA2 (iv) a pore diameter such that at least 10 percent of the pores are less than 55 .ANG., and PA2 (i) a mean particle size from about 10 .mu.m to about 200 .mu.m, PA2 (ii) a fractional porosity of at least 0.2, PA2 (iii) a surface area of at least 150 m.sup.2 /g, and PA2 (iv) a pore diameter such that at least 10 percent of the pores are less than 55 .ANG., PA2 (i) an alumina existing in a crystal form selected from the group consisting of .gamma., .delta., .eta., and .chi. crystal forms, and mixtures thereof, or that can be transformed by heat to such crystal forms, and characterized by PA2 (ii) at least one metal oxide, or compound convertible by heat to such metal oxide, having a maximum mean particle size of about 100 .mu.m, with the proviso that the alumina/metal oxide mean particle size ratio is at least 2, which metal oxide is susceptible of undergoing infusion and reaction with the alumina upon being subjected to temperatures of at least 0.4 T.sub.m for a time sufficient to cause infusion and reaction between the metal oxide and the alumina, wherein T.sub.m is the melting point in .degree.K. of the alumina, and PA2 (i) mean particle size from about 10 .mu.m to about 200 .mu.m, PA2 (ii) a fractional porosity of at least 0.2, PA2 (iii) a surface area of at least 150 m.sup.2 /g, and PA2 (iv) a pore diameter such that at least 10 percent of the pores are less than 55 .ANG., and
The attrition resistant metal/oxygen compositions of this invention may be used for any of a wide variety of purposes generally known in the art. Thus, for example, the compositions are useful in the transformation of numerous organic compounds in the vapor phase such as dehydrogenation reactions, oxidation reactions, hydrogenation reactions, isomerization reactions, dealkylation reactions, dehydrocoupling reactions, and the like. The compositions may be employed in a manner identical to that for metal/oxygen compositions heretofore known in the art for such transformations.
2. Description of the Prior Art
Supported metal oxides are well-known as catalysts and oxygen carriers for a wide variety of chemical reactions. In general, such metal oxide compositions are comprised of a metal oxide coated on a support material of low porosity and low surface area. Such support is commonly referred to as an inert support. The method generally employed to produce these supported metal oxide compositions involves impregnating the inert support with a solution of a soluble salt of the metal oxide, separating the resultant impregnated solid, and heating to remove a substantial portion of the solvent. The impregnated solid is then calcined at elevated temperatures to convert the metal salt to the corresponding metal oxide. Multiple impregnations are sometimes employed to achieve an increased concentration of metal oxide on the support.
Another well-known technique employed for forming supported metal oxide compositions involves suspending the support materials in a solution of a salt of the metal, completely or partially evaporating the solvent, and possibly mixing the resultant material with an organic binder and pelletizing thereof. The dry pellet is then heated to an elevated temperature to effect complete dehydration and burning out of the organic material.
A method for forming a supported metal oxide on a porous support is disclosed in U.S. Pat. No. 3,925,447 which involves contacting the porous support material with the metal oxide in molten form to produce a catalyst in which the metal oxide is substantially entirely within the pores of the support. The resultant catalyst is used in the production of nitriles.
U.S. Pat. No. 3,668,151 discloses a high strength (as indicated by its crush strength) zinc aluminate catalyst composition. Upon being impregnated with platinum, lithium, and tin in the usual manner, the resultant catalyst was used to dehydrogenate n-butane to olefins and diolefins, presumably 1- and 2-butene and 1,3-butadiene.
A substantially identical zinc aluminate catalyst having an approximate mole ratio of zinc oxide to alumina of 1 also is disclosed in U.S. Pat. No. 4,260,845. The catalyst is reported to be useful for dehydration of saturated alcohols to olefins, for example, 2-methyl-1-butanol to 2-methyl-1-butene.
Although these prior art compositions are generally suitable for their stated purposes, the commercial utility of catalysts and oxygen carrier compositions in reactions which involve reaction conditions of high stress (such as high temperatures and/or pressures, especially under fluidized bed conditions) require compositions which are highly resistant to abrasion and attrition due to the deleterious effects of reaction conditions. Accordingly, research efforts are continually being made for high efficiency catalyst and oxygen carrier compositions of increased physical strength and attrition resistance which are useful in reactions involving conditions of high stress. The discovery of the compositions of the present invention, therefore, is believed to be a decided advance in the catalyst and oxygen carrier composition art.